Process of preparing wood products



.March 30, 1943. F, KRE5SMAN 2,315,372

\ PRocEssoF PREPARING woon PRODUCTS Filed Nov.- s, 193s 2 sheets-sheet 1 lll x o r A ,MHH HI' l- I Tw m IN VENT OR.

Q v v A mimlw Q A ,A A LJ ATTORNFYS.

Poema Mar. 30,1943

PROCESS F PBEIABING WOOD PRODUCTS Frederick W., Krcssman, Laurel, Misa., assignor 'to Continental 'lnrpentine l RolinCorp. Ine.,

Laurel, Mis s.,.a corporation of Mississippi NT ori-ICE Application November 3, 1938,?Sem No. 238,688

ciali-is. (ci. zee-.sr Y

and used' m the mixing of rubber. itis admirably' rI'his invention relates to a process of preparing a' wood product, and more piuticul'arlyto a process of preparing highly absorbent wood fibers o'f substantially uniform density.

process of the invention.

to remove the solvent.

carded or used for fuel.

- come adapted to many uses.

roonng felt.

the solvent.

material.

Although the Banbury machine was designed for adapted to this purpose.

In operation. .the pieces ofwood are subjected to frictional contact with twol irregularly shaped members, which arev rotated within the mixing For convenience in loading, I prefer Most oils are suitable lubricants for The Banbury machina. through its The resulting temperature rise in lthe Most of thedisintegration takes'place To distinguish from these and tion, and then steaming, whenapplied to the One feature of this invention is that a process 5 is disclosed to obtain a wood product of substanchamber.

l' tially uniform absorbent quality. Other features to add to the Banbury machinean additional and advantages will be apparent from the specifichamber of approximately .the same size as the cation and the drawings, in which: mixing chamber. The additional chamber may Fig. 1 is a plan view of an air classifier; Fig. 2 10 be used as a reservoir, containing a completel is a side elevationalv view; Fig. 3 is an end elevacharge ready for introduction into vthe mixing tion: Fig. 4 is a sideelevational View. partly in chamber. v section. all of the same device; and Fig. 5 is a dia- The rotating members in the Jmixing chamber grammatic view showing broadly the steps of the subject the wood to frictional, twisting, shearing.

' 16 shredding contact with each other and with the It has long been common in the artto treat walls of the chamber.- This action serves to rewood, such as yellow pine, to obtain therefrom duce the wood to the fibrous form with a miniturpentine, rosin and other organic'products. It mum vof tearing, lacerating or breaking of Vthe has been the'practice to take stumps of yellow` fibers. Most of the disintegration is eilected along pine or other suitable wood of little value, and theline ofthe grain of the wood.

f reduce the material .to small chips by a hogging In order to further reduce thelaceration or .or shredding operation. The chips are steamed breaking -of the fibers, it is preferable to carry toremove turpentine and other'volatile'organic out the brating action in the presence of a compounds, then extracted with anv organic sollubricant. vent to obtain therosin, and finally steamed again '-5 this purpose. However, in the fibrating of wood V After these operations, containing a large amount of rosin, such as yellow the chips have no further usefulness and are dispine for example, the rosin in the wood acts as a lubricant.

I have found that these chips may be reduced frictional action, develops a considerable amount to a fibrous absorbent form'and in this state be- 3u of heat.

For instance, .the mixingchamber increases the effectiveness of the, product may be used as an absorbent material in rosin as a lubricant.

j If the temperature of-the mixing chamber is Even when the wood is properly reduced to the I controlled, itv should not be maintained at less fibrous form, extraction is desirable to provide a :lo than 200-215"- F. The high pressure which is maximum absorbent equality.v Not only are the developed in the process is also an aid in reducing organic liquids, which are removed, of great value, the wood to fibrous form. but the resulting product is much more porous. The product of the Banbury machine consists In udditOIly man? ysmall hard non-absorbent parof long thin bers -of wood with smaller fibers fieles result flOm the bratn DIOCeSS T0 Ob- '40 extending therefrom, referred to herein as bundles tain a satisfactory product, it is necessary that of fibers. these be separated from the fibrous material. along the lines of the grain of the wood. As a I have found that wood, preferably in the form result, thefibers are of relatively small dimenof chips or other small pieces,may be fibratedto sions transverse Ato, the grain.. Such bers are' obtain anabsorbent product. At this point the highly absorbent and porous. as compared to sawwood may be extracted with a suitableorganic dust or other forms of wood reduced vto small solvent, land then treated with steam to remove particles, such as the products of a grinding or The non-absorbent particles should attritionl mill. then be separated from the resulting product, in other methodsY of reducing wood to small particles, order vto obtainl a commercially useful absorbent .I refer to the process of reducing wood to fibrous form by a Banbury mixer or like machine as a The process of iibrating the wood may be carried wood flbrating process. out in a Banburyv mixer, such as that described in The former process for recovering organic liq- Patent No. 1,523,387, or other suitable machine. nids from the wood, to-wit: steaming, extrac- 'as 1 per cent.

rated-by fractional distillation. The organic solvent may be removed from the bers by subjecting them to steam, or, if it is not desirable to attempt to recover the solvent, merely by al conventional drying operation. l

The extracted iibrated product is in a highly absorbent porous condition and contains, after the steaming operation, a high percentage of moisture usually about 40 per cent. It may be rent of air evenly along the lower surface of the table. The air then flows through a series of transverse. apertures, such as the aperture II..

in the table, and through any material which may have been deposited on the table.

In operation, theiibrated extracted wood product'is fed into the hopper III and fromthere deposited upon the table II' adjacent the guards 24 and 25. The reciprocal agitation of the table IIA gradually carries the material towards the guard 23. In the meanwhile, the rapidly flowing current of air being blown through the material raises the particles of low density above the series of rillies 26 and 21 and permits them to pass down the sides I3 and 22 of the table II to the receptacles on either side.

placed in a conventional dryer and the moisture content reduced to approximately 15 per cent. The step of separation ofundesirable particles by means of an air classifier may be carried out with material having a moisture content as low On the other hand the same step may be carried out with material having a high moisture content although 35 per cent or'more of moisture is undesirable. However, for most eficient results, I prefer to reduce the moisture only to between V12 per cent and 20 per cent.

Many of the particles found in the product are, however, relatively non-absorbent, and the product as a whole isunsatisfactory for commercial use unless these particles are removed. The absorbent qualities are not related to the size of the particles, but are' directly related to their density.

By treating the iibrated product with Aan air classiiier, substantially all of the non-absorbent particles may be removed. By the term airclassifier is meant a device which, by passing the particles through a rapidly iiowing current of air, separates them according to their densities. A specific air classiiier, for example, is disclosed herein.

peak I2 the side I3 of the table II is inclined downwardly to the receptacles I4 to 2 I inclusive,

` and the side 22 is inclined downwardly to similar receptacles on the other side o f the table. At-

the end of the table opposite the hopper I0 a V- shaped guard 23 prevents material from passing I over the end of the table. Guards 24 and 25, mounted adjacentthe hopper I0, serve the same purpose at the other end.

The top surface of the table I I supports a'series of rifiles or fins 23 and 21 on either side of the peak. The riiiies are higher at one end than the other and are mounted in such a manner that the higher ends are .adjacent to the guards 2l and 25. The lower ends approach the center line of the table. Therefore,"since the riilies 21 are in a position vsubstantially parallel to each other. they are graduated in length in order that none may cross the center line of the table.

The table II is agitated or shaken bythe eccentric 28, driven by the motor 29,. and connected 'd to the table Il by the member 30. Resilient sliding rocker arms K3| and 32 aid in controlling the motion. i.

A ian 33 forces a rapidlyiiowing current of air through the flexible duct 3l into the-chamber 35. Deiiectors or louvers 35 and 31 carried by the base of the table tend to distribute the cur- The product collected in the receptacles Il to I8, inclusive, is of substantially uniform density rial is also the most readily dried. Thus, when the iibrated extracted product leaves the drier, the non-absorbent particles will contain some- -what more moisture than the desired product.

Since moisture increases 'the density of the product, this aids in the separation. Therefore, itis preferable that the average moisture content of the particles be at least 15 per cent when the particles leave the drier.

The final product consists of a wood product in the form of long, thin, porous. highly absorbent fibers from'which substantially all of theorganic substances, originally absorbed by the wood, have been removed. The bundles of fibers retain most of their original strength and are substantially uniform' in absorbent quality. This product is extremely useful in any instance where a relatively inexpensive absorbent material is needed. For instance, this material may be used to partially or wholly replace the rag content of waterproof roofing felts.

Theforegoing detailed description has been lgiven for cleamess of understanding only, and no greater density than the highly iibrous particles;-

treating the brated product with moisture until moisture content of the wood is materially above 20%;' heating the product to vremove a portion of the moisture therefrom and reduce the moisture content of the product as a whole to between 12% and 20% whereby the diiierentialA in density between the vparticles isincreased; and

thereafter passing the partially dried product through a rapidly moving current of air to remove. therefrom the particles of relatively high density.A v 2. A process of the character described for v'fpreinaring highly absorbent cellulose material from wood. comprising fibrating the wood to form fibrous particles of different absorbent'.

"quantities, the major portion of the particles being highly fibrous in character and other particles being woody and less fibrous and having a greater density than the highly fibrous particles, treating the brated product with steam to increase the moisture content to the neighborhood of 40%, drying the product in an oven to Aremove therefrom a substantial portionof the vmoisture obtained from the steam, .reducing the moisture content to between 12% and l 20% whereby the density differential between the particles is increased, passing. the partially dried product through a rapidly moving current of air whereby the particles of relatively high density 15 are separated from vthe particles of relatively low density, and collecting separately the fibrous parthe fibers of low density are separated from the fibers of high density, and collecting separately the fibers of substantially uniformly low density, 4. AA-process of` the character described for- Preparing highly absorbent cellulose material from wood, comprising brating the Woodto form brous particles of diierent absorbent quantities, the major portion of the particles lief ing highly fibrous in character and other particles being woody and less fibrous and having a ,greater density than the highly fibrous particles, treating all of the fibrated particles with moisture under substantially uniform conditions to introduce a relatively large percentage of moisture into the product, subjecting all of the particles to substantially uniform drying-conditions to ma.-

terially reduce the moisture content of the particles 'whereby an increase in the density diiferl entiai between the highly fibrous particles and the less brous woody particles is effected, and subjecting the mixture of particles to air table classification to separate the particles of low density' from the particles of. high density.

5. A process for separating highly absorbent wood fibers from other particles that are woody and less fibrous into bundles of substantially uniform density, comprising treating the wood fibers with moisture until the fibers absorb a substantial quanity thereof and containing in excess of 15% of moisture, drying the product to re duce the moisture contentof the fibersy as a whole t0 approximately 15%, and passing the partially dried product through a rapidly moving current of air whereby the bundles of bers of relatively low density are4 separated from the bundles o "`'relatively high density.

FREDERICK W. KREssMAN. 

